We walked upstairs. The room in which the crime had been committed was obvious: it was flanked by two burly constables.

Lestrade nodded to the men, and they stood aside. We walked in.

I am not, as I said, a writer by profession, and I hesitate to describe that place, knowing that my words cannot do it justice. Still, I have begun this narrative, and I fear I must continue. A murder had been committed in that little bedsit. The body, what was left of it, was still there, on the floor. I saw it, but, at first, somehow, I did not see it. What I saw instead was what had sprayed and gushed from the throat and chest of the victim: in color it ranged from bile-green to grass-green. It had soaked into the threadbare carpet and spattered the wallpaper. I imagined it for one moment the work of some hellish artist who had decided to create a study in emerald.

After what seemed like a hundred years I looked down at the body, opened like a rabbit on a butcher’s slab, and tried to make sense of what I saw. I removed my hat, and my friend did the same.

He knelt and inspected the body, examining the cuts and gashes. Then he pulled out his magnifying glass, and walked over to the wall, examining the gouts of drying ichor.

“We’ve already done that,” said Inspector Lestrade.

“Indeed?” said my friend. “What did you make of this, then? I do believe it is a word.”

Lestrade walked to the place my friend was standing, and looked up. There was a word, written in capitals, in green blood, on the faded yellow wallpaper, some little way above Lestrade’s head. “R-A-C-H-E…?” said Lestrade, spelling it out. “Obviously he was going to write ‘Rachel,’ but he was interrupted. So-we must look for a woman…”